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University of Gezira (2018

Ecology, Biology and Chemical Control of Cotton Mealybug Phenacoccus solenopsis(Tinsley) on some Vegetable Crops, Gezira State, Sudan

Elobeid, Amna Elobeid Mohammed

Titre : Ecology, Biology and Chemical Control of Cotton Mealybug Phenacoccus solenopsis(Tinsley) on some Vegetable Crops, Gezira State, Sudan

Auteur : Elobeid, Amna Elobeid Mohammed

Université de soutenance : University of Gezira

Grade : Master of Science (MS) in Crop Protection 2018

Résumé
The recent out-break of cotton mealybug (CMB), Phenacoccus solenopsis(Tinsley) on many crops belong to different families was making a real worry for farmers and researcher. Tomato and eggplant were attacked by this invasive pest. The objectives of this work were to study the biology, ecology and chemical control on tomato and eggplant. Laboratory and semi-field trials beside field surveys were conducted with consideration to the temperature and relative humidity (RH) during the period of the study. The results revealed that on tomato : the mean period for the first, second, third instar, pre-oviposition, oviposition and post-oviposition were 4.5±1.29, 6.6±2.07, 6.0±2.16, 3.2±1.31, 3.7±1.77, 2.9±1.12 respectively. The total life cycle was 26.9±9.72 days. On eggplant the period was 6.0±1.56, 9.5±2.87, 10.3±3.29, 3.0±0.9, 4.33±1.72, 2.66±0.85 respectively. The total life cycle was 35.79±11.22 days. The female of (CMB) was found to lay only one ovisack on both tomato and eggplant. The number of nymphs/ovisack ranged between 30- 475 nymphs. During the winter season, the mean number of cotton mealybug (MCNMB) and the infestation level of cotton mealybug (ILCMB) were highest (20–100 insect/15cm), (80-100%) for tomato and eggplant respectively in March where the temperature was ranged between 25–35ºc and the (RH) 20–30 %, and lowest (0-10 insect/15cm ) , (30–90 %) respectively in January where the temperature ranged between 20–25ºc and (RH) 30–40 %. While during the rainy season the (MNCMB) and (ILCMB) were highest (20–60 insect/15cm ), (60-100%) respectively from September to November where the temperature range between 10- 20ºc and (RH) 40–60% and lowest (0-10 insect/15cm ), (5–80%) respectively on both tomato and eggplant in August where the temperature was 10 -30ºc and RH 70-80%. The predators recorded attacking (CMB) were : Exochomus nigromuculatus and Scymnus sp. The insecticides treatments show that : Selecton at double and recommended dose was the best one of the tested insecticides followed by the Diazinon and Sinomat with mortality% after 72 hrs : (100% , 85%), (97% , 90%),and (82%, 82%) respectively. When the LD90 was optimized and compared with the recommended dose show that : the LD90 of Diazinon was the only one less than the recommended dose. So, the insecticides ( Diazinon, Sinomat, and Selecton ) were recommended to control CMB on vegetables using recommended dose after testing on large scale field experiments. Also, it can be concluded that : the (MNCMB) and (ILCMB) record higher levels when the temperature was high and the RH is low. All these results were discussed and compared with the previous studies.

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Page publiée le 7 décembre 2018